Date: Tue, 16 Sep 1997 22:07:21 -0700 (PDT) From: Doug White <dwhite@gdi.uoregon.edu> To: Luigi Rizzo <luigi@labinfo.iet.unipi.it> Cc: lamaster@george.arc.nasa.gov, multimedia@FreeBSD.ORG Subject: Re: X11 video grabber for vic... Message-ID: <Pine.BSF.3.96.970916220029.4310Y-100000@localhost> In-Reply-To: <199709161920.VAA06208@labinfo.iet.unipi.it>
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Want to add a bit here. On Tue, 16 Sep 1997, Luigi Rizzo wrote: > You can of course put all of this in the videoconferencing program, but > why bother, since these are in a sense orthogonal features (I know not > completely, there is the quality/fps issue but that could also be made > adaptive, e.g. the threshold could be lowered when the traffic goes > down and increased when it goes too up...) ? Actually, vic does support this to an extent. It gets better if you increase the quality level just a smidge (-1 or 2 points), but if you hold the camera on a object, vic will improve the quality of the transmitted image, and inversley, if the image is changing rapidly, vic will back off the quality of the image until it stabilizes again. vic will only back off the quality a set amount. If it is on the lowest possible setting, then vic is very insensitive to movement and the backoff isn't very noticable since it only drops to the equivalent of quality 4 or 5 or so until the image stabilizes. Now, on quality 10, it can drop back to 14 or so, which is barely any clarity at all but excellent framerate. So setting the quality really low will only hurt you in a condition such as a conference; ideally, they should be running at 5 or so with a really crisp video camera. This assumes that the input image is of excellent quality; using cheap cameras and/or video capture boards with poor resolution doesn't help things. I get excellent results using an old VHS camcorder and my Bt848 even on the default setting. Doug White | University of Oregon Internet: dwhite@resnet.uoregon.edu | Residence Networking Assistant http://gladstone.uoregon.edu/~dwhite | Computer Science Major Spam routed to /dev/null by Procmail | Death to Cyberpromo
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